IR imaging equipment (e.g., IR cameras) may be employed to capture information regarding IR emissions in the electromagnetic (EM) spectrum for environments of interest (EOI), and to make observations about objects of interest (OOI) or targets of interest (TOI) within those environments. An object (e.g., OOI, TOI, etc.) may be distinguished from its environment (i.e., background) by observing differences in the IR emissions between the object and its background (e.g., objects, materials, etc.). Because IR emissions are at least partially related to temperature of an object, the IR imaging equipment can indirectly measure the thermal profile of an object by detecting IR emissions within the field of view of the IR imaging equipment.
There are situations in which it may be desirable to cloak the detection of the IR emissions of an object, such as during combat. For example, passive infrared (PIR) devices may be used to detect IR emissions, and may be further configured to trigger improvised explosive devices (IEDs) when a difference in temperature is detected from the background temperature, such as, for example, when a hot engine of a vehicle travels down the road. Military vehicles such as high mobility multipurpose wheeled vehicles (HMMWV), armored vehicles (e.g., Buffalo), and other similar vehicles may have their IR signatures masked (i.e., matched to the IR signature of the background), which may protect the vehicle from detection by IR imaging equipment. The temperature of the vehicle may be adjusted in order to mask the IR signature of the engine for a period of time long enough to drive through choke point suspected to be secured with PIR devices and IEDs. Another combat situation involves weapons systems that use IR detection as a seeking method or for terminal guidance to “look” for TOIs, which have IR emissions that are different from the background. In order to hide the TOI from such weapons systems, the IR signature of the TOI, or an object placed in front of the TOI, may be matched with the IR signature of the background.
Conventional methods for cloaking an object in the IR spectrum include matching the reflectivity of an object. Matching reflectivity of an object may be desirable for situations in which the user of IR imaging equipment relies on an outside IR source to illuminate the objects for detection; however, not all IR imaging equipment relies on outside IR sources to illuminate the objects for detection. Other conventional methods may match the IR emissions over a fixed wavelength range of the IR spectrum. The inventors have appreciated that there is a need for improved methods for cloaking objects from detection within the IR spectrum.